Dog-faced Fruit Bat Research Articles

Bat diversity and its distribution in Mount Gutom Protected Landscape, Zamboanga del Norte, Philippines

Abstract. Lama JMN, Caballero EB, Mondejar EP. 2023. Bat diversity and its distribution in Mount Gutom Protected Landscape, Zamboanga del Norte, Philippines. Biodiversitas 24: 5495-5502. Bats play an indispensable role in the balance of the ecosystem in their habitats, which range from the seaside to mountains, caves, and rivers. This study surveyed the flying mammals of Mt. Gutom Protected Landscape, Zamboanga del Norte, Philippines, on April 12-23 and December 7-20, 2022. Mist netting was used to sample bats at the four sampling sites, with a total sampling effort of 126 net-nights. A total of eight species (n=330 individuals) representing two families was recorded. This includes Lesser Dog-faced fruit bat (Cynopterus brachyotis), Philippine Dawn bat (Eonycteris robusta), Philippine Pygmy fruit bat (Haplonycteris fischeri), Harpy fruit bat (Harpyionycteris whiteheadi), Dagger-toothed long-nosed fruit bat (Macroglossus minimus), Greater Musky fruit bat (Ptenochirus jagori), Lesser Musky fruit bat (P. minor), and Horsfield’s myotis (Myotis horsfieldii). The Lesser Dog-faced fruit bat (Cynopterus brachyotis) was the most abundant species in Mt. Gutom, with relative abundance of 40.91% (n=135 individuals). Mt. Gutom also supports endemic species, with 62.5% endemicity, and a Vulnerable species (Eonycteris robusta) was documented only in Site 2 (a mixed secondary dipterocarp forest). Moreover, sampling site 3 (secondary dipterocarp forest) recorded the highest abundance (RA=44.24%) and species diversity index (H’=1.376) among the four sampling sites. The results suggest that Mt. Gutom supports a diverse species of bats and conservation measures are needed to protect the remaining habitats in the area.

Power requirements for bat-inspired flapping flight with heavy, highly articulated and cambered wings.

Bats fly with highly articulated and heavy wings. To understand their power requirements, we develop a three-dimensional reduced-order model, and apply it to flights of Cynopterus brachyotis, the lesser dog-faced fruit bat. Using previously measured wing kinematics, the model computes aerodynamic forces using blade element momentum theory, and incorporates inertial forces of the flapping wing using the measured mass distribution of the membrane wing and body. The two are combined into a Lagrangian equation of motion, and we performed Monte Carlo simulations to address uncertainties in measurement errors and modelling assumptions. We find that the camber of the armwing decreases with flight speed whereas the handwing camber is more independent of speed. Wing camber disproportionately impacts energetics, mainly during the downstroke, and increases the power requirement from 8% to 22% over flight speed U = 3.2-7.4 m s-1. We separate total power into aerodynamic and inertial components, and aerodynamic power into parasitic, profile and induced power, and find strong agreement with previous theoretical and experimental studies. We find that inertia of wings help to balance aerodynamic forces, alleviating the muscle power required for weight support and thrust generation. Furthermore, the model suggests aerodynamic forces assist in lifting the heavy wing during upstroke.

Low-Order Modeling of Flapping Flight with Highly Articulated, Cambered, Heavy Wings

A three-dimensional low-order modeling technique is described for modeling both wing inertial and aerodynamic forces of animals and robots flapping heavy and morphing wings. The model is applied to prescribed kinematics from a previously measured flight of a lesser-nosed, dog-faced fruit bat (Cynopterus brachyotis) in straight and climbing flight. Quasi-steady blade element momentum theory is used to model the aerodynamic forces of the highly articulated wing, and a Lagrangian equation of motion is adopted to describe the overall wing–body dynamics that includes the wing inertia. These two distinct and independent models yield a good prediction of the thrust/drag balance, and are in excellent agreement of lift production. Unique to this approach, the quantitative effect of wing camber was examined within the framework, which contributes as much as 27% of the cycle-averaged lift, with a smaller price (10%) paid to drag.

Detection and characterization of a novel bat-borne coronavirus in Singapore using multiple molecular approaches.

Bats are important reservoirs and vectors in the transmission of emerging infectious diseases. Many highly pathogenic viruses such as SARS-CoV and rabies-related lyssaviruses have crossed species barriers to infect humans and other animals. In this study we monitored the major roost sites of bats in Singapore, and performed surveillance for zoonotic pathogens in these bats. Screening of guano samples collected during the survey uncovered a bat coronavirus (Betacoronavirus) in Cynopterus brachyotis, commonly known as the lesser dog-faced fruit bat. Using a capture-enrichment sequencing platform, the full-length genome of the bat CoV was sequenced and found to be closely related to the bat coronavirus HKU9 species found in Leschenault’s rousette discovered in the Guangdong and Yunnan provinces.

Bats are unusually insensitive to brief low-frequency tones.

Bats use brief calls for echolocation, suggesting that they might be more sensitive to brief sounds than non-echolocating mammals. To investigate this possibility, absolute thresholds for brief tones were determined for four species of bats: The Commonvampire bat (Desmodus rotundus) and the Greater spear-nosed bat (Phyllostomus hastatus), both of which use frequency-modulated calls, the Egyptian fruit bat (Rousettus aegyptiacus), an echolocator that uses tongue-clicks rather than laryngeal calls, and the Dog-faced fruit bat (Cynopterus brachyotis), a non-echolocating species. Norway rats and a human were tested for comparison using the same acoustic stimuli. Contrary to expectations, the echolocating bats were not superior to non-echolocating mammals in detecting brief tones in the frequency range of their echolocation calls. Instead, all four species of bats were remarkably less sensitive than non-bats to brief sounds of 10kHz and below. This implies that temporal summation in the mammalian auditory system can show large species differences, and that the detection of brief sound is likely influenced by the selective pressures on each species as well as by the physical integration of energy in the auditory system. Such species differences in function are expected to be reflected in the physiology of their auditory systems.

<b>Foraging and roosting ecology of the Lesser Dog-faced Fruit Bat <I>Cynopterus brachyotis</I> (Mammalia: Chiroptera: Pteropodidae) in southern India</b>

The Lesser Dog-faced Fruit Bat Cynopterus brachyotis was found at higher elevations but since there is a paucity of reports on its distribution and habitat selection, an inventory was made at four locations in the Eastern and Western Ghats of southern India where the elevation ranged from 200–1,500 m. The C. brachyotis roosts were distributed between 600–1,500 m. Day roosts were found at an elevation of about 1,000m in Sirumalai and Yercaud Hill stations. Mist-netting studies, however, revealed that C. brachyotis was widely distributed at different elevations ranging from 600–1,500 m. Moreover, through a radio-telemetry study, we determined that the males foraged at shorter distances from the day roost, whereas the females commuted longer distances and used more than one foraging area. The male bats’ time of emergence is significantly less than females; in addition, males frequently return to their day-roost and made several short foraging flights spaced randomly throughout the night. These observations suggest that some type of territoriality is associated with their roost, which appears to be the basis of social organization in C. brachyotis. Overall, this study provides detailed information about the foraging and roosting ecology of C. brachyotis in southern India.

Hindlimb motion during steady flight of the lesser dog-faced fruit bat, Cynopterus brachyotis.

In bats, the wing membrane is anchored not only to the body and forelimb, but also to the hindlimb. This attachment configuration gives bats the potential to modulate wing shape by moving the hindlimb, such as by joint movement at the hip or knee. Such movements could modulate lift, drag, or the pitching moment. In this study we address: 1) how the ankle translates through space during the wingbeat cycle; 2) whether amplitude of ankle motion is dependent upon flight speed; 3) how tension in the wing membrane pulls the ankle; and 4) whether wing membrane tension is responsible for driving ankle motion. We flew five individuals of the lesser dog-faced fruit bat, Cynopterus brachyotis (Family: Pteropodidae), in a wind tunnel and documented kinematics of the forelimb, hip, ankle, and trailing edge of the wing membrane. Based on kinematic analysis of hindlimb and forelimb movements, we found that: 1) during downstroke, the ankle moved ventrally and during upstroke the ankle moved dorsally; 2) there was considerable variation in amplitude of ankle motion, but amplitude did not correlate significantly with flight speed; 3) during downstroke, tension generated by the wing membrane acted to pull the ankle dorsally, and during upstroke, the wing membrane pulled laterally when taut and dorsally when relatively slack; and 4) wing membrane tension generally opposed dorsoventral ankle motion. We conclude that during forward flight in C. brachyotis, wing membrane tension does not power hindlimb motion; instead, we propose that hindlimb movements arise from muscle activity and/or inertial effects.

Design and characterization of a multi-articulated robotic bat wing

There are many challenges to measuring power input and force output from a flapping vertebrate. Animals can vary a multitude of kinematic parameters simultaneously, and methods for measuring power and force are either not possible in a flying vertebrate or are very time and equipment intensive. To circumvent these challenges, we constructed a robotic, multi-articulated bat wing that allows us to measure power input and force output simultaneously, across a range of kinematic parameters. The robot is modeled after the lesser dog-faced fruit bat, Cynopterus brachyotis, and contains seven joints powered by three servo motors. Collectively, this joint and motor arrangement allows the robot to vary wingbeat frequency, wingbeat amplitude, stroke plane, downstroke ratio, and wing folding. We describe the design, construction, programing, instrumentation, characterization, and analysis of the robot. We show that the kinematics, inputs, and outputs demonstrate good repeatability both within and among trials. Finally, we describe lessons about the structure of living bats learned from trying to mimic their flight in a robotic wing.

Kinematic plasticity during flight in fruit bats: individual variability in response to loading.

All bats experience daily and seasonal fluctuation in body mass. An increase in mass requires changes in flight kinematics to produce the extra lift necessary to compensate for increased weight. How bats modify their kinematics to increase lift, however, is not well understood. In this study, we investigated the effect of a 20% increase in mass on flight kinematics for Cynopterus brachyotis, the lesser dog-faced fruit bat. We reconstructed the 3D wing kinematics and how they changed with the additional mass. Bats showed a marked change in wing kinematics in response to loading, but changes varied among individuals. Each bat adjusted a different combination of kinematic parameters to increase lift, indicating that aerodynamic force generation can be modulated in multiple ways. Two main kinematic strategies were distinguished: bats either changed the motion of the wings by primarily increasing wingbeat frequency, or changed the configuration of the wings by increasing wing area and camber. The complex, individual-dependent response to increased loading in our bats points to an underappreciated aspect of locomotor control, in which the inherent complexity of the biomechanical system allows for kinematic plasticity. The kinematic plasticity and functional redundancy observed in bat flight can have evolutionary consequences, such as an increase potential for morphological and kinematic diversification due to weakened locomotor trade-offs.

Wake structure and wing kinematics: the flight of the lesser dog-faced fruit bat,Cynopterus brachyotis

We investigated the detailed kinematics and wake structure of lesser dog-faced fruit bats (Cynopterus brachyotis) flying in a wind tunnel. High speed recordings of the kinematics were conducted to obtain three-dimensional reconstructions of wing movements. Simultaneously, the flow structure in the spanwise plane perpendicular to the flow stream was visualized using time-resolved particle image velocimetry. The flight of four individuals was investigated to reveal patterns in kinematics and wake structure typical for lower and higher speeds. The wake structure identified as typical for both speed categories was a closed-loop ring vortex consisting of the tip vortex and the limited appearance of a counter-rotating vortex near the body, as well as a small distally located vortex system at the end of the upstroke that generated negative lift. We also investigated the degree of consistency within trials and looked at individual variation in flight parameters, and found distinct differences between individuals as well as within individuals.

Bat Coronaviruses and Experimental Infection of Bats, the Philippines

Fifty-two bats captured during July 2008 in the Philippines were tested by reverse transcription-PCR to detect bat coronavirus (CoV) RNA. The overall prevalence of virus RNA was 55.8%. We found 2 groups of sequences that belonged to group 1 (genus Alphacoronavirus) and group 2 (genus Betacoronavirus) CoVs. Phylogenetic analysis of the RNA-dependent RNA polymerase gene showed that groups 1 and 2 CoVs were similar to Bat-CoV/China/A515/2005 (95% nt sequence identity) and Bat-CoV/HKU9-1/China/2007 (83% identity), respectively. To propagate group 2 CoVs obtained from a lesser dog-faced fruit bat (Cynopterus brachyotis), we administered intestine samples orally to Leschenault rousette bats (Rousettus leschenaulti) maintained in our laboratory. After virus replication in the bats was confirmed, an additional passage of the virus was made in Leschenault rousette bats, and bat pathogenesis was investigated. Fruit bats infected with virus did not show clinical signs of infection.

Do fruit bats deserve to be listed as vermin in the Indian Wildlife (Protection) & Amended Acts? A critical review

Of the 13 species of fruit bats occurring in India, the Indian flying fox Pteropus giganteus, the dog-faced fruit bat Rousettus leschenaultii and the greater short-nosed fruit bat Cynopterus sphinx are distributed throughout the country. They usually live in trees (P. giganteus), temples and caves (R. leschenaultii) and foliage (C. sphinx) and feed on fruits such as fig Ficus spp., Singapore cherry Muntingia calabura, Indian almond Terminalia catappa, mango Mangifera indica, guava Psidium guajava as well as leaves, nectar and pollen. The other 10 species live at sea level and at altitudes of > 2,000 m and their distribution and foraging activities may be restricted mainly to forests. Two of them, the Nicobar flying fox Pteropus faunulus and Salim Ali's fruit bat Latidens salimalii are endemic. Although details of their foraging activity are poorly known, there is no evidence that they visit commercial fruit orchards. They feed on wild fruits and disperse seeds widely, contributing to forest regeneration. Although P. giganteus, R. leschenaultii and C. sphinx feed on commercial fruits, their role in pollination and seed dispersal of economically important plants such as kapok Ceiba pentandra, mahua Bassia latifolia and petai Parkia spp. is important. Sacrificial crops such as M. calabura can be used at orchards to reduce the damage bats cause to commercial fruit. Because the ecological services provided by bats are not appreciated by the public and conservation planners, all fruit bat species with one exception are still categorized as vermin and included as such in Schedule V of the Indian Wildlife (Protection) Act, 1972 and amended Acts. It is now appropriate for the Government of India to revisit this issue and consider removing these pollinators and seed dispersers from the list of vermin in the Wildlife (Protection) Act.

Sound localization acuity and its relation to vision in large and small fruit-eating bats: II. Non-echolocating species, Eidolon helvum and Cynopterus brachyotis

Passive sound-localization acuity for 100-msec noise bursts was determined behaviorally for two species of non-echolocating bats: the Straw-colored fruit bat, Eidolon helvum, a large frugivore, and the Dog-faced fruit bat, Cynopterus brachyotis, a small frugivore. The mean minimum audible angle for two E. helvum was 11.7°, and for two C. brachyotis was 10.5°. This places their passive sound-localization acuity near the middle of the range for echolocating bats as well as the middle of the range for other mammals. Sound-localization acuity varies widely among mammals, and the best predictor of this auditory function remains the width of the field of best vision ( r = .89, p < .0001). Among echolocating and non-echolocating bats, as well as among other mammals, the use of hearing to direct the eyes to the source of a sound still appears to serve as an important selective factor for sound localization. Absolute visual acuity and the magnitude of the binaural locus cues available to a species remain unreliable predictors of sound-localization acuity.

Hearing in large ( Eidolon helvum) and small ( Cynopterus brachyotis) non-echolocating fruit bats

Comparing the hearing abilities of echolocating and non-echolocating bats can provide insight into the effect of echolocation on more basic hearing abilities. Toward this end, we determined the audiograms of two species of non-echolocating bats, the straw-colored fruit bat ( Eidolon helvum), a large (230–350 g) African fruit bat, and the dog-faced fruit bat ( Cynopterus brachyotis), a small (30–45 g) bat native to India and Southeast Asia. A conditioned suppression/avoidance procedure with a fruit juice reward was used for testing. At 60 dB SPL, the hearing range of E. helvum extends from 1.38 to 41 kHz with best sensitivity at 8 kHz; the hearing range of C. brachyotis extends from 2.63 to 70 kHz with best sensitivity at 10 kHz. As with all other bats tested so far, neither species was able to hear below 500 Hz, suggesting that they may not use a time code for perceiving pitch. Comparison of the high-frequency hearing abilities of echolocating and non-echolocating bats suggests that the use of laryngeal echolocation has resulted in additional selective pressure to hear high frequencies. However, the typical high-frequency sensitivity of small non-echolocating mammals would have been sufficient to support initial echolocation in the early evolution of bats, a finding that supports the possibility of multiple origins of echolocation.

SEM study on the dorsal lingual surface of the large flying fox, Pteropus vampyrus.

The dorsal lingual surface of the large flying foxes were examined by scanning electron microscopy. Filiform, fungiform and vallate papillae were observed. The filiform papillae were distributed over the entire dorsal surface of the tongue. The filiform papillae notably differed in morphology by their location on the tongue and could be classified into 6 types: 1) scale-like, 2) giant trifid, 3) small crown-like, 4) large crown-like, 5) long conical and 6) short conical papillae. The fungiform papillae were present rounded bodies on the anterior 2/3 of the tongue. The large flying foxes showed the triangular arrangement of the three vallate papillae, with the apex of the triangle directed posteriorly. These findings indicate that the tongue of the large flying bat is similar to that of the lesser dog-faced fruit bat.

SEM study on the dorsal lingual surface of the lesser dog-faced fruit bat, Cynopterus brachyotis.

The dorsal lingual surface of the lesser dog-faced fruit bat was examined by scanning electron microscopy (SEM). Filiform (Fi), fungiform (Fu) and vallate papillae (V) were observed. The Fi papillae were distributed over the entire dorsal surface of the tongue. The Fi papillae notably differed in morphology by their location on the tongue and could be classified into 5 types: 1) crown-like papillae, 2) giant trifid papillae, 3) scale-like papillae, 4) small conical papillae, and 5) large conical papillae. The Fu papillae were present rounded bodies on the anterior 2/3 of the tongue. The lesser dog-faced fruit bat showed the triangular arrangement of the three V, with the apex of the triangle directed posteriorly.

Tent construction and social organization in Cynopterus brachyotis (Muller) (Chiroptera: Pteropodidae) in Peninsular Malaysia

This study examined the tent-making behaviour and social organization of the lesser dog-faced fruit bat, Cynopterus brachyotis (Muller), in Peninsular Malaysia. Cynopterus brachyotis alters the leaves of eight species of broad-leafed palms (Palmae) to form palmate umbrella tents, the leaves of Scindapsus aureus Engl. (Araceae) to form apical tents, and the leaves of Dracaena fragrans Ker-Gawl (Liliaceae) to form conical tents. Cynopterus brachyotis also severed the roots of Cymbidium finlaysonianum Lindl (Orchidaceae), and the leaves and stems of Philodendron lacerum Schott (Araceae) to form stem tents. In addition, C. brachyotis also roosted in unmodified plants. Cynopterus brachyotis possesses a harem type of social organization, but it was not possible to distinguish between a resource-defence polygyny and female-defence polygyny mating system. Our observations indicate that dominant males construct tents, and recruit females for the purpose of gaining reproductive access.